A and B are two taps which can fill a tank in 6 hourse and 9 hours, respectively. C is an emptying tap, which can empty the tank in `7.5` hourse Tap B is opened 3 hours after tap A is opened. For how long does tap C to be ketp opne if the tank has to be filled in 6 hours ?

Options

A. `1(1)/(2)` hours
B. `2(1)/(2)` hours
C. 3 hours
D. 5 hours

Answer

B

Explanation

(i) Tap A is opend for 6 hours and Tap Fror 3 hours.
(iii) Let C be opened for x hours.
(iii) Solve `(6)/(6)+(3)/(9)-(x)/(7.5)=1`, for x